Subject: man for timerate (doc/timerate.n)

From: sebres <[email-masked]>
Date: Thu, 11 May 2017 09:46:43 +0000

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+'\"
+'\" Copyright (c) 2005 Sergey Brester aka sebres.
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\"
+.TH timerate n "" Tcl "Tcl Built-In Commands"
+.so man.macros
+.BS
+'\" Note:  do not modify the .SH NAME line immediately below!
+.SH NAME
+timerate \- Time-related execution resp. performance measurement of a script
+.SH SYNOPSIS
+\fBtimerate \fIscript\fR \fI?time?\fR
+.sp
+\fBtimerate \fI?-direct?\fR \fI?-overhead double?\fR \fIscript\fR \fI?time?\fR
+.sp
+\fBtimerate \fI?-calibrate?\fR \fI?-direct?\fR \fIscript\fR \fI?time?\fR
+.BE
+.SH DESCRIPTION
+.PP
+The first and second form will evaluate \fIscript\fR until the interval
+\fItime\fR given in milliseconds elapses, or for 1000 milliseconds (1 second)
+if \fItime\fR is not specified. 
+.sp
+It will then return a canonical tcl-list of the form
+.PP
+.CS
+\f0.095977 µs/# 52095836 # 10419167 #/sec 5000.000 nett-ms\fR
+.CE
+.PP
+which indicates:
+.IP \(bu
+the average amount of time required per iteration, in microseconds (lindex $result 0)
+.IP \(bu
+the count how many times it was executed (lindex $result 2)
+.IP \(bu
+the estimated rate per second (lindex $result 4)
+.IP \(bu
+the estimated real execution time without measurement overhead (lindex $result 6)
+.PP
+Time is measured in elapsed time using heighest timer resolution as possible, not CPU time.
+This command may be used to provide information as to how well the script or a tcl-command 
+is performing and can help determine bottlenecks and fine-tune application performance.
+.PP
+\fI-calibrate\fR
+.
+To measure very fast scripts as exact as posible the calibration process
+may be required.
+
+This parameter used to calibrate \fBtimerate\fR calculating the estimated overhead 
+of given \fIscript\fR as default overhead for further execution of \fBtimerate\fR.
+It can take up to 10 seconds if parameter \fItime\fR is not specified.
+.PP
+\fI-overhead double\fR
+.
+This parameter used to supply the measurement overhead of single iteration 
+(in microseconds) that should be ignored during whole evaluation process.
+.PP
+\fI-direct\fR
+.
+Causes direct execution per iteration (not compiled variant of evaluation used).
+.PP
+In opposition to \fBtime\fR the execution limited here by fixed time instead of 
+repetition count.
+Additionally the compiled variant of the script will be used during whole evaluation 
+(as if it were part of a compiled \fBproc\fR), if parameter \fI-direct\fR is not specified.
+Therefore it provides more precise results and prevents very long execution time 
+by slow scripts resp. scripts with unknown speed.
+
+.SH EXAMPLE
+Estimate how fast it takes for a simple Tcl \fBfor\fR loop (including
+operations on variable \fIi\fR) to count to a ten:
+.PP
+.CS
+# calibrate:
+timerate -calibrate {}
+# measure:
+timerate { for {set i 0} {$i<10} {incr i} {} } 5000
+.CE
+.PP
+Estimate how fast it takes for a simple Tcl \fBfor\fR loop only (ignoring the 
+overhead for operations on variable \fIi\fR) to count to a ten:
+.PP
+.CS
+# calibrate for overhead of variable operations:
+set i 0; timerate -calibrate {expr {$i<10}; incr i} 1000
+# measure:
+timerate { for {set i 0} {$i<10} {incr i} {} } 5000
+.CE
+.PP
+Estimate the rate of calculating the hour using \fBclock format\fR only, ignoring 
+overhead of the rest, without measurement how fast it takes for a whole script:
+.PP
+.CS
+# calibrate:
+timerate -calibrate {}
+# estimate overhead:
+set tm 0
+set ovh [lindex [timerate { incr tm [expr {24*60*60}] }] 0]
+# measure using esimated overhead:
+set tm 0
+timerate -overhead $ovh {
+    clock format $tm -format %H
+    incr tm [expr {24*60*60}]; # overhead for this is ignored
+} 5000
+.CE
+.SH "SEE ALSO"
+time(n)
+.SH KEYWORDS
+script, timerate, time
+.\" Local Variables:
+.\" mode: nroff
+.\" End:
-- 
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